Click a letter to see a list of conditions beginning with that letter.

Click 'Topic Index' to return to the index for the current topic.

Click 'Library Index' to return to the listing of all topics.

Small for Gestational Age

What is small for gestational age?

Small for gestational age is a term used to describe babies that are smaller than usual for the number of weeks of pregnancy. These babies have birth weight below the 10th percentile. This means they are smaller than many other babies of the same gestational age. Most babies normally weigh more than 5 pounds, 13 ounces by the 37th week of pregnancy. Babies born weighing less than 5 pounds, 8 ounces are considered low birth weight.

What causes small for gestational age?

Some babies are small because their parents are small. But most babies who are small for gestational age have growth problems that happen during pregnancy. Many of these babies have a condition called intrauterine growth restriction. This happens when the unborn baby doesn’t get the nutrients and oxygen needed to grow and develop organs and tissues. This can begin at any time in pregnancy.

Growth restriction early in pregnancy (early onset) happens because of chromosome problems in the baby. It also happens because of disease in the mother,or severe problems with the placenta. Growth restriction is called late onset if it happens after week 32 of the pregnancy. It is usually related to other problems.

Who is at risk for small for gestational age?

When the unborn baby doesn’t get enough oxygen or nutrients during pregnancy, the baby’s overall body and organs don't grow as much as they should. Some of the problems that cause small for gestational age and intrauterine growth restriction limit how much blood flows through the placenta. This can cause the baby to get less oxygen than normal. This increases the baby’s risks during pregnancy and delivery, and later. Things that can cause small for gestational age are listed below.

Problems with the mother

High blood pressure

Chronic kidney disease

Diabetes

Heart disease or respiratory disease

Malnutrition or anemia

Infection

Alcohol or drug use

Cigarette smoking

Weighing less than 100 pounds

Problems with the uterus and placenta

Decreased blood flow in the uterus and placenta

Placenta detaches from the uterus

Placenta attaches low in the uterus

Infection in the tissues around the baby

Problems with the developing baby

Multiple pregnancy, such as twins or triplets

Infection

Birth defects

Chromosome problems

What are the symptoms of small for gestational age?

Small for gestational age babies may look mature, but they are smaller than other babies of the same gestational age. They may be small all over, or they may be of normal length and size but have lower weight and body mass. These babies may be born:

Premature. Before 37 weeks of pregnancy.

Full-term. Between 37 to 41 weeks.

Post-term. After 42 weeks of pregnancy.

Many small for gestational age babies have low birth weight. But not all are premature. They may not have the same problems as premature babies. Other babies, especially those with intrauterine growth restriction, may look thin and pale, and have loose, dry skin. The umbilical cord is often thin and dull-looking rather than shiny and fat.

How is small for gestational age diagnosed?

Babies with this problem are often diagnosed before birth. During pregnancy, a baby’s size can be guessed in different ways. The height of the top of a mother’s uterus can be measured from the pubic bone. This measurement in centimeters usually links with the number of weeks of pregnancy after the 20th week. If the measurement is low for the number of weeks, then the baby may be smaller than expected.

Other procedures used for diagnosis may include:

Ultrasound to estimate the baby’s size

Doppler flow to help see intrauterine growth restriction during pregnancy

Mother’s weight gain to tell a baby's size

Baby’s birth weight as compared with the gestational age. The healthcare provider may use a formula to figure out the baby’s body mass.

How is small for gestational age treated?

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.

Babies with this problem may be physically more mature than their small size shows. But they may be weak and less able to take large feedings or stay warm. Treatment may include:

Temperature-controlled beds or incubators

Tube feedings if the baby does not have a strong suck

Blood tests to check for low blood sugar

Watching oxygen levels

Babies who are also premature may have other needs. They may need oxygen and a breathing machine (ventilator).

What are the complications of small for gestational age?

Babies who are small for gestational age or who have intrauterine growth restriction may have problems at birth. These can include:

Lower oxygen levels than normal

Low Apgar scores

Breathing in the first stools (meconium) passed in the womb. This can cause breathing problems.

Low blood sugar

Difficulty keeping a normal body temperature

Too many red blood cells

Can small for gestational age be prevented?

Prenatal care is important in all pregnancies. It is especially helpful to see any problems with the baby’s growth. For a healthy pregnancy, stop smoking if you smoke, and don't use drugs or alcohol while you are pregnant. Eating a healthy diet during pregnancy may also help.

Key points about small for gestational age

Small for gestational age means a baby who is smaller than expected for the number of weeks of pregnancy.

Although some babies are small because their parents are small, most babies who are small for gestational age have growth problems that happen during pregnancy.

When the unborn baby does not get enough oxygen or nutrients during pregnancy, he or she does not grow as much as normal.

The condition is often found before birth.

Prenatal care is important in all pregnancies. It is especially helpful to see any growth problems of the developing baby.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

Know the reason for the visit and what you want to happen.

Before your visit, write down questions you want answered.

At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.

Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.

Ask if your child’s condition can be treated in other ways.

Know why a test or procedure is recommended and what the results could mean.

Know what to expect if your child does not take the medicine or have the test or procedure.

If your child has a follow-up appointment, write down the date, time, and purpose for that visit.

Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.